medwireNews: Age, gender, and exophytic properties may help clinicians predict benign histology in patients with T1a renal cell carcinomas (RCCs), suggest findings published in the International Journal of Urology.

"These three factors may help to select patients who should undergo biopsy before partial nephrectomy," says Kouji Izumi (Kanazawa University Graduate School of Medical Science) in a related Editorial Comment.

The frequency of benign lesions has previously been reported to be relatively low in Asian patients and this was borne out in the current study, with a rate of just 8.1% among 149 patients (49 women) aged 23-81 years undergoing partial nephrectomy for T1a RCC.

But Izumi stresses that "this incidence should not be disregarded and urologists should avoid unnecessary surgery."

Multivariate analysis indicated younger age and female gender significantly predicted benign lesions. A total of 4% of men and 16% of women had benign lesions.

The effect of these factors could be explained by the large proportion of angiomyolipomas (3.35%), "which are obviously more frequent in younger women than common sporadic RCC," say the study authors, led by Tetsuo Fujita (Kitasato University School of Medicine).

Lesions that were at least 50% exophytic were also more likely to be benign than other lesions. In all, 66.7% of benign lesions were exophytic, compared with 29.9% of cancerous lesions.

"Accordingly, the frequency of benign histological findings was higher in the [laparoscopic partial nephrectomy] cohort than in the [open partial nephrectomy] cohort (13.0% vs 2.8%)," note the researchers.

They admit that "the reason for the correlation between exophytic tumor property and benign histological findings is hard to explain."

And Izsumi recommends further pathological and etiological research "to elucidate the mechanisms underlying this interesting phenomenon."